Method for the polymerization of isoolefin

ABSTRACT

A METHOD FOR PRODUCING ISOOLEFIN HOMOPOLYMERS OR COPOLYMERS IS PROVIDED HEREIN, WHICH COMPRISES PLYMERIZING OR COPLYMERIZING AN ISOOLEFIN, A MIXTURE THEREOF, OR A MIXTURE OF AN ISOOLEFIN AND DIOLEFIN COPOLYMERIZABLE THEREWITH IN THE PRESENCE OF A CATALYST SYSTEM COMPRISING (1) A METAL ORGANIC AMIDE REPRESENTED BY THE GENERAL FORMULA, M(NR2)MXN, WHEREIN M IS A METAL ATOM, M+N IS THE VALENCE OF THE METAL ATOM, R IS AN ALKYL RADICAL HAVING FROM 1 TO 12 CARBON ATOMS, AN ARYL RADICAL HAVING FROM 6 TO 10 CARBON ATOMS, AN ARALKYL RADICAL HAVING FROM 7 TO 12 CARBON ATOMS, A CYCLOALKYL RADICAL HAVING FROM 6 TO 10 CARBON ATOMS, OR A HALOGENATED, SUBSTITUTED THEREOF, AND R&#39;&#39;S MAY BE THE SAME OR DIFFERENT, AND X IS A HALOGEN ATOM, AND (2) BORON TRIFLUORIDE. THE PRESENT INVENTION IS ALSO DIRECTED TO THE ABOVE-DEFINED CATALYST COMBINATION, PER SE, USEFUL FOR PRODUCING ISOOLEFIN POLYMERS. BY THE USE OF THE ABOVE CATALYST SYSTEM IT IS POSSIBLE TO PRODUCE ISOOLEFIN POLYMERS HAVING A HIGH DEGREE OF POLYMERIZATION AT COMPARATIVELY HIGHER TEMPERATURES THAN CONVENTIONAL CATALYST SYSTEMS.

United States Patent "US. Cl. 26085.3 R 13 Claims ABSTRACT OF THE DISCLOSURE A method for producing isoolefin homopolymers or copolymers is provided herein, which comprises polymerizing or copolymerizing an isoolefin, a mixture thereof, or a mixture of an isoolefin and diolefin copolymerizable therewith in the presence of a catalyst system comprising (1) a metal organic amide represented by the general formula, M(NR X wherein M is a metal atom, m+n is the valence of the metal atom, R is an alkyl radical having from 1 to 12 carbon atoms, an aryl radical having from 6 to 10 carbon atoms, an aralkyl radical having from 7 to 12 carbon atoms, a cycloalkyl radical having from 6 to 10 carbon atoms, or a halogenated substituted thereof, and Rs may be the same or diiferent, and X is a halogen atom, and (2) boron trifluoride. The present invention is also directed to the above-defined catalyst combination, per se, useful for producing isoolefin polymers. By the use of the above catalyst system it is possible to produce isoolefin polymers having a high degree of polymerization at comparatively higher temperatures than conventional catalyst systems.

This invention relates to a method of polymerizing an isoolefin. More particularly, the present invention relates to a method of producing isoolefin homopolymers or copolymers, namely butyl type rubbers, which comprises polymerizing or copolymerizing an isoolefin, a mixture thereof, or a mixture of an isoolefin and a multiolefin in the presence of a particular catalyst system.

A number of catalyst systems for producing butyl type rubber have hitherto been proposed. For example, metal halides of the Friedel-Crafts type catalyst have been proposed. Among these, a solution of aluminum chloride in methyl chloride or in ethyl chloride has been most frequently used for the production of butyl type rubbers. However, these catalysts require a temperature as low as about -l00 C. Such a low temperature is not desirable from an industrial or economic point of view.

Thus, many attempts have been made to produce, at a comparatively high temperature, isoolefin polymers of a high degree of polymerization suitable for practical use. For example, as for the methods for producing high molecular weight isobutylene polymers at a comparatively high temperature, there is known a method of polymerizing isobutylene in the presence of a catalyst system of Et AlC1- tert.-BuCl in a polar solvent such as methylene chloride (Japanese patent publication No. 2,471/1969) or in the presence of a catalyst system of Al(0 sec.-butyl) BF TiCl (J. Polymer Sci., 53, 281).

It is an object of the present invention to provide a method of producing isoolefin homopolymers or copoly- .mers having a high degree of polymerization.

Another object of the invention is to provide isobutylene homopolymers or copolymers having a high degree of polymerization.

Still another object of the invention is to provide a butyl type rubber of a high molecular weight, namely a copolymer of isoolefin such as isoutylene and a multiolefin copolymerizable therewith such as isoprene, at a considerably higher temperature than that which has been possible hitherto.

Other objects and advantages will be apparent from the following description.

We have now found that the us of a catalyst system comprising (1) a metal organic amide and (2) boron trifluoride is effective for producing isoolefin homopolymers or copolymers having a high molecular weight at a comparatively higher temperature than that required when a Friedel-Crafts type catalyst such as boron trifluoride or aluminum chloride is singly employed.

The present invention is based on the above discovery and relates to an improved method of producing isoolefin homopolymers or copolymers. The method comprises polymerizing or copolymerizing an isoolefin, a mixture thereof, or a mixture of an isoolefin and a multiolefin copolymerizable therewith in the presence of a catalyst system comprising (1) a metal organic amide represented by the general formula M(NR X wherein M is a metal atom, m-I-n is the valence of the metal atom, R is an alkyl radical having from 1 to 12 carbon atoms, an aryl radical having from 6 to 10 carbon atoms, an aralkyl radical having from 7 to 12 carbon atoms, a cycloalkyl radical having from 6 to 10 carbon atoms or a halogenated substitute thereof, and Rs may be same or difierent, and X is a halogen atom, and 2) boron trifiuoride.

The metal atom in the metal organic amide is Zn, Al, Ti, Sn, Si, Zr, etc. and R represents an alkyl radical such as methyl, ethyl, u-propyl, isopropyl, n-butyl, sec-butyl, tart-butyl, n-amyl, iso-amyl, n-hexyl, isohexyl, n-heptyl, n-octyl, 2-ethylhexyl, etc.; a cycloalkyl radical such as cyclopentyl, methylcyclopentyl, etc.; an aryl radical such as phenyl, toluyl, Xylyl, cumenyl, naphthyl, etc.; an aralkyl radical such as benzyl, phenethyl, etc. and a halogen substitute thereof. X represents F, Cl, Br and I.

Representative examples of the metal organic amide having the above general formula are Zn(N iso-buty1 Zn(N ethy12)2, n-butyl P11611342) A1(N y 2)1.5 1.5

Ti(N ethyl Si(N ethyl and Zr(N n-butyl Any of these compounds, when used alone, has no catalytic activity to polymerize isobutylene, but when used in combination with boron trifluoride exhibits a catalytic activity quite difierent from the known Friedel- Crafts type catalysts, and enables the production of isobutylene polymers of a high degree of polymerization even at a comparatively high temperature.

The metal organic amide to be used in the present invention can be synthesized for example, by reacting a lithium amide LiNR (produced by the reaction of an organic radical disubstituted amine HNR with metallic lithium) with a metal chloride, and also can be easily synthesized by reacting an alkyl metal MR or an alkyl metal halide MR X wherein R is an alkyl radical, with an organic radical disubstituted amine HNR Many of these metal organic amides i.e. M(NR ),,,X can be purified by distillation. They are also easily soluble in many inert solvents such as hydrocarbons (for example, n-heptane, benzene and the like) and halogenated hydrocarbons (for example, methyl chloride, ethyl chloride and the like). Thus, they are convenient when supplied to a polymerization system or when polymerized, because of their solubility in such solvents. In addition, in the polymerization, even by the further addition of boron fluoride, these amides do not form any precipitate and therefore do not cause uneven polymerization. Thus, the catalysts of the present invention may be advantageously separated from the reaction system after the polymerization.

The isoolefins to be used in the present invention are those having from 4 to 8 carbon atoms. Representative examples of these compounds include isobutylene, 2- methyl-l-butene, 3-methyl-1-butene, 2-methyl-2-butene, 4- methyl-1-pentene and a mixture thereof. Also cationic ample, benzene, toluene and the like) and mixtures thereof.

The amount of the catalyst to be used in the present invention is from 2 to 0.001% by mole, preferably from 1 to 0.01% by mole for the organic metal amide compolymerizable compounds, for example, styrene, a-methyl- 5 pound and from to 0.001% by mole, preferably from styrene and the like can also be used as isoolefins. 5 to 0.02% by mole, for boron trifluoride, based on the The multiolefins copolymerizable with the above destarting material. scribed isoolefins are those having from 4 to 14 carbon For carrying out smoothly the method of the present atoms. Representative examples of these compounds in- 10 invention, either the bulk or solution polymerization can clude isoprene, 1,3-butadiene, 2,3-dimethyl-1,3-butadicne, be selected and the polymerization may be conducted 6,6-dimethylfulvene, piperylene, cyclopentadiene, dicyclobatchwise or continuously. pentadiene, divinylbenzene, cyclohexadiene, vinylcyclo- When polymerizing by using the catalyst system of the hexene, and the like. present invention, the polymerization can be accelerated The butyl type rubbery polymers can be obtained by 15 or controlled by the presence of a polar substance such copolymerizing isoolefin as a major part of the total comas, water, alcohols, organic carboxylic acids, etc. Such pounds used, for example in an amount of from about has been well known for the Friedel-Crafts type catalysts 70 to 99.5% by weight, preferably from 85 to 99.5% by and this is also the case for the catalyst system of the weight with a multiolefin as a minor part, for example in present invention. an amount of from about 30 to 0.5% by weight, prefer- The polymerization temperature is generally below 0 ably from 15 to 0.5% by weight. Particularly preferred C., but the temperature can be suitably selected accordpolymers are obtained by copolymerizing from 95 to .ing to the desired properties of the polymer. 995% by weight f i b t l n ith f 5 t 05% by The following examples are given for the illustration i ht f isoprene, purpose only and not for limiting the scope of the inven- Isoolefins, even in their single use, can be polymerized tion in any way. to produce useful polymers. For example isobutylene, when polymerized singly, forms polyisobutylene of a high Examples and Comparatlve Example 1 degree of polymerization. Isoolefin may be also copolymerized with other polymerizable monoolefins such as To a 300 flask lsobutylepe and 150 styrenen-heptane were charged. Further, 0.5 milllmole of a metal Further y the use of the catalyst System of this organic amide was added and cooled to a polymerization present invention, useful and low molecular weight p01y temperature. While stirring this reaction solution, an mers can also be obtained. When a considerable amount amount of BF3 mtfodflced Into the upper Space of f a lti l fi f example 30 to 5% by Weight f the flask. After polymer1zat1on for one hour, ethanol was prene, is copolymerized with isoolefin, for example 70 adfied to Stop h reactlonon freeze-drying the thus to 95% by weight of isobutylene, at any desired tempertamed polymerized Substance one y, a White ature, butyl rubbers having a low, number average molecbery P y Was Obtained. The results are shown in ular weight of 1000 to 50,000 can produced i yrup- Table 1 together with the result obtained in Comparative or grease-like form. As they have a narrow width of Example 1 in which a metal organic amide was not molecular weight distribution, they are low in spinnabil- 40 added.

TABLE 1 Commpl parativc 1 2 a 4 5 6 7 Exampli Metal organic amide. A B G D E F G H BFa(mili1nole) 8 4.5 12 4.5 2.7 4.5 4.5 4.5 4.5 Polymerization temperature C.) -65 65 65 65 65 65 65 65 Yield (g. 29. 29.2 15.9 33.0 16.0 29.5 30.5 25.3 23.1 Viscosity average molecular weight (thousand)-. 600 1,010 850 1,100 320 720 910 530 95 ity and are therefore easy to process into elastic sealants with or without dilution in a solvent. Their high strength after vulcanization seems to result from comparatively uniform lengths of the molecule.

The polymerization is generally conducted in an inert solvent so as to facilitate the operation. Any type of solvent which is inert under the polymerization conditions can be used. Examples of such solvents are conventional halogenated hydrocarbons (for example, methyl chloride, ethyl chloride, chlorobenzene, methyl bromide and carbon tetrachloride), carbon disulfide, saturated hydrocarbons (for example, n-hexane, n-heptane and the like), unsaturated hydrocarbons (for example, ethylene, propylene and the like), aromatic hydrocarbons (for ex- Examples 9-11 and Comparative Example 2 To a 300 ml. flask, 33.7 g. isobutylene, 0.67 g. isoprene and 150 ml. n-heptane were charged. Further, 0.5 millimole of a metal organic amide was added and cooled to a polymerization temperature. While being stirred this reaction solution, an amount of BF was introduced into the upper space of the flask. After polymerization for one hour, ethanol was added to stop the reaction. On freeze-drying the thus obtained polymerized substance for one day, a white rubbery polymer was obtained. The results are shown in Table 2 together with the result of Comparative Example 2 in which a metal organic amide was not added.

TABLE 2 Example Comparative 9 10 Example 2 Metal organic amide....:..;.-.;.-. Zn(N Eta): Zn(N 150-B112): Ti(N Et2)4 BF; (millimnle) r 8 9 8 4,0 Polymerization temperature 0.). 76 65 Yield (g.) I 30. 8 30.3 28. 1 23. 5 Viscosity average molecular weight (thousand)-...- 540 680 480 12 Double bond content (percent isoprene mole content) Examples 12-14 andCom'p'arativ'e Example 3:

Toe 30?) 1111. flask", 33.7 g. isobutylene, 0.68 g. isoprene-and 150-ml. methyl chloride 'were charged. Then, an amount of metal organic amide was added thereto.

copolymers, which comprises polymerizing or copolymerizing an isoolefin, a mixture thereof, or a mixture of an isoolefin and a diolefin copolymerizable therewith in'the presence of a catalyst system comprising (1) a metal While being stirred and cooled, BF was introduced into 5 organic amide represented by the general formula: the upper space of the flask. After polymerization for M NR X one hour, ethanol was added to stop the reaction. On n freeze-drying the thus obtained polymerized substance for wherein M is a metal atom, m-l-n is the valence of the one day, a white rubbery polymer was obtained. The remetal atom, R is an alkyl radical having from 1 to 12 sults are shown in Table 3 together with the result of carbon atoms, an aryl radical having from 6 to 10 car- Comparative Example 3 in which a metal organic amide bon atoms, an aralkyl radical having from 7 to 12 carbon was not added. atoms, a cycloalkyl radical having from 6 to 10 carbon TABLE 3 Example Comparative ex- 12 13 14 ample3 Metal organic amide *I Zn(N1s0-Bu1)1 Ti(N Et1)1 BF; (millimole) 8 9 B 4 Polymerization temperature C.) -78 -78 ---"78 78 Yield (g.) 26.6 31.0 27.1 30.2 Viscosity average molecular weight (thousand) 680 800 620 98 3352?Tiff???.ifffiiifiifi ii 1 18 1.13 1.11 1.23

It is apparent from Examples l-14 according to the method of the present invention that the higher molecular weight polymers than those obtained in Comparative Ex amples 1-3 in which the BF catalyst was used singly were obtained.

Examples 15-16 TABLE 4 Example 15 16 Metal organic amide Al(N Et2) ,5Cl 5 Zn(N iso-Bum BF 1(mi11imole) 4. 5 6. 2 2-methylbutene-1 (g.) 30.1 30. 1 Isoprene (g.) 16. 0 Polymerization temperature (0.) -45 -45 Viscosity average molecular weight (thousand) 230 110 Double bond content (percent isoprene mole) 0. 7

Example 17 To a 300 ml. flask, 33.7 g. isobutylene and 2.55 g. isoprene were charged. 150 ml. n-heptane was added and then 0.5 millimole Zn(N iso-Bu was added. After cooling the mixture to 75 C. while being stirred, 9 millimoles of BF was introduced. After polymerization for two hours, methanol was added to stop the reaction. On freeze-drying at 55 C. under reduced pressure, 28.1 g. of a semi-fluid polymer was obtained. The double bond content was 4.2 isoprene percent by mole, the viscosity average molecular weight 32,000, and the molecular weight distribution coefiicient (weight average molecular weight/number average molecular weight) 3.2.

What is claimed is:

1. A method for producing isoolefin homopolymers or atoms, or a halogenated substitute thereof, and Rs may be same or different, and the X is a halogen atom, and (2) boron trifluoride.

2. A method according to claim 1 wherein the isoolefin is a member selected from the group consisting of iso butylene, Z-methylbutene-l, 3-methylbutene-l, Z-methylbutene-2 and 4-methylpentene-1.

3. A method according to claim 1 wherein the diolefin is a member selected from the group consisting of isoprene, butadiene-1,3, 2,3-dimethylbutadiene-1,3, 6,6-dimethylfulvene, piperylene, cyclopentadiene, dicyclopentadiene, divinylbenzene, cyclohexadiene and vinylcyclohexene.

4. A method according to claim 1 wherein 70 ot 99.5% by weight of the isoolefin is copolymerized with 30 to 0.5 by weight of the diolefin.

5. A method according to claim ll wherein to 99.5 by weight of isobutylene is copolymerized with from 5 to 0.5% by weight of isoprene.

6. A method according to claim 1 wherein the metal atom M is a member selected from the group consisting of Zn, Al, Ti, Si and Zr.

7. A method according to claim 1 wherein the metal organic amide is a member selected from the group consisting of Zn(N iso-butyl Zn(N ethyl Zn(N ny ah, p y zh N y 2)1.5 1.51 ethyl Si(N ethyl and Zr(N n-butyl 8. A method according to claim 1 wherein the metal organic amide is used in an amount from 2 to 0.001 mole percent based on the starting monomer.

9. A method according to claim 1 wherein boron trifluoride is used in an amount of from 10 to 0.001 mole percent based on the starting monomer.

10. A method according to claim 1 wherein the polymerization or copolymerization is carried out in the presence of a solvent.

11. A method according to claim 10 wherein the solvent is at least one selected from the group consisting of methyl chloride, chlorobenzene, ethylchloride, carbon tetrachloride, carbon disulfide, n-hexane, n-heptane, ethylene, propylene, benzene and toluene.

12. A method according to claim 1 wherein the polymerization is carried out at a temperature below 0 C.

13. A catalyst consisting essentially of (1) a metal organic amide represented by the general formula,

wherein M is a metal atom selected from the group consistign of Zn, Al, Ti, Sn and Zr, m+n is the valence of the metal atom, R is an alkyl radical having 1 to 12 carbon atoms, an aryl radical having 6 to 10 carbon, atoms, an aralkyl radical having 7 to 12 carbon atoms, a cycloalkyl radical having 6 to 10 carbon atoms, or a halogen substitute thereof, the Rs being present in a total number of 2m per molecule may be same or different, and X is a halogen atom, and (2) boron trifluoride.

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1/1973 Cucinella et a1. 260-853 R 5 JOSEPH L. SCHOFER, Primary Examiner A. HOLLER, Assistant Examiner US. Cl. X.R. 0

252-431 N, 433; 260-882 B, 93.7, 94.8, 94.9 B 

